single or double acting cylinder??

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Originally Posted by Blknight.aus

the combination double acting Ram and hand pump cylinders are usually sold as a unit as the head of the pump cylinder has a 4port 2 position valve built into it. This controls the direction of flow of the oil from the pump to one side of the RAM and the other side of the ram to the tank.

because of the intergral valve and tank setup of the single acting cylinders pump you cant just put that pump onto the double acting cylinder. You can do it but you have to mod the tank and fit a secondary valve that does the return to tank function.

you can get a single acting pump that has a reversing valve in it that has a "suction" function that reverses the flow of the pump and pulls the oil from the cylinder and puts it into the tank. They work resonably well untill the seal on the RAM starts to weep and it then sucks a little air into the cylinder and you loose the prime on the pump.

IF it was me and the double acting ram was the primary requirement and the minimum cost was the aim ID

fit AG ram or a double acting ram from something like a grader. plumb in a 2port 2 position spool valve that swaps the A+B ports across the T and P ports. Fit a powersteering pump thats got a remote resivior from something like say a D2 and run it off of a small 12v motor or fit up a hand crank.

without the Ram depending on your scrounging skill should cost you sub $200

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Dave,

Do you think he would get 50T on a reasonable size ram with a powersteering pump?

Just had a quick look and found a 2500 psi pump on ebay they say can be used on a log splitter. That is about 1.13T/in^2. So the size of the ram to get 50T would need to be about 45 in^2, that is approx 7.5" diam ram. That is a big ram so you might need a bit more pressure out of your pump. I have no idea what a PS pump can generate.

A 7" bore with a 1" rod at 3000psi will push 115000lb and pull 113000lb (52 & 51T respectively).

wow, lots of good info there guys, thanks.

a few things.

Id like to keep my system/s interchangable. Ie as I already have some hyd stuff, keep the new stuff to suit. I have an air/hyd pump and 10t ram on a bender. Im happy to use a hand pump on the press for a couple of reasons, 1: the feel or touch is sometimes needed rather than a push button and 2: with quick fittings I can take the pump off and use it as a porta pac type deal with other cylinders.

Double acting is not a requirement for me , unless it is.....by that I mean as long as the single acting cylinder (with internal spring) is going to return (even slowly) it will be ok....Id rather buy good quality less features over average quality more features...

the reason I ask about using a hand pump that is designed for double acting cylinders, on a single acting cylinder, is that if one comes up for the right price I figured it would be good for down the track if I did end up needing a double acting cylinder for something???

cheers, Serg

You could get creative with other ways to create a mechanical return if spring/s weren't going to do the job.
Something like a small hand winch with wire cable might be reasonably practical. I've used old presses in the past that have this as a method of raising/lowering the press bed. Cheap boat winch would do the job.

I'd also put a pressure gauge on the ram pressure side if you haven't already got one. Doesn't matter so much with a smaller press, but with bigger ones I reckon its nice to know how much force you are applying.
This ties in with your "feel" comment too.

Steve

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Originally Posted by uninformed

wow, lots of good info there guys, thanks.

a few things.

Id like to keep my system/s interchangable. Ie as I already have some hyd stuff, keep the new stuff to suit. I have an air/hyd pump and 10t ram on a bender. Im happy to use a hand pump on the press for a couple of reasons, 1: the feel or touch is sometimes needed rather than a push button and 2: with quick fittings I can take the pump off and use it as a porta pac type deal with other cylinders.

Double acting is not a requirement for me , unless it is.....by that I mean as long as the single acting cylinder (with internal spring) is going to return (even slowly) it will be ok....Id rather buy good quality less features over average quality more features...

the reason I ask about using a hand pump that is designed for double acting cylinders, on a single acting cylinder, is that if one comes up for the right price I figured it would be good for down the track if I did end up needing a double acting cylinder for something???

cheers, Serg

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the double acting cylinders pump can be used to drive a single acting cylinder you just need a blanking plug to place in one of the outputs of the pump